GHC/Type system

From HaskellWiki

1 Type system extensions in GHC

GHC comes with a rather lare collection of type-system extensions (beyond Haskell 98). They are all documented in the user manual, but this page is a place to record observations, notes, and suggestions on them.

1.1 Overlapping instances

Here an interesting message about the interaction of existential types and overlapping instances.